docs: def add_parameter(self, field_name, param_name, param_value):
          """
          Add a parameter to a field into script_fields
  
          The ScriptFields object will be returned, so calls to this can be chained.
          """
          try:
              self.fields[field_name]['params'][param_name] = param_value
          except Exception as ex:
              raise ScriptFieldsError("Error adding parameter %s with value %s :%s" % (param_name, param_value, ex))
  
          return self